Organic polymers each containing at least one reactive silicon group in the molecule thereof are known to have interesting characteristics such that they are cross-linked even at room temperature by forming siloxane bonds accompanied by hydrolysis reaction of the reactive silicon groups due to the moisture or the like to yield a rubber-like cured substance.
Among such reactive silicon group-containing organic polymers, polyoxyalkylene polymers and polyisobutylene polymers are disclosed in Japanese Patent Laid-Open Nos. 52-73998, 5-125272, 3-72527, 63-6003, 63-6041, 1-38407, 8-231758 and the like, and have already been manufactured industrially and have been widely used in applications as sealants, adhesives, painting materials and the like.
Curing compositions which contain these reactive silicon group-containing organic polymers are cured by use of silanol condensation catalysts; usually, organotin catalysts having carbon-tin bonds such as dibutyltin bisacetylacetonate are widely used. Curing compositions using organotin catalysts are generally excellent in curability and yield cured substances tending to undergo stress relaxation. However, in these years alternative catalysts are demanded from the viewpoint of the environmental protection. Additionally, catalytic systems free from the heavy metals of the fourth period or higher in the periodic table are demanded.
As such non-organotin catalysts, divalent tin carboxylates and bismuth carboxylates and other various metal carboxylates have been proposed as described in Japanese Patent Laid-Open No. 55-9669, Japanese Patent No. 3062626, and Japanese Patent Laid-Open Nos. 6-322251 and 2000-345054.
Additionally, among curing catalysts free from heavy metals are catalytic systems concomitantly using carboxylic acids and amine compounds as described in Japanese Patent Laid-Open No. 5-117519.
However, when the catalysts described in the aforementioned patents involving the metal carboxylates and carboxylic acids are used, there has been a problem that the curability is lower and the adhesion is also somewhat lower than when organotin catalysts are used.
On the other hand, Japanese Patent Laid-Open Nos. 2000-345054 and 5-117519 and Japanese Patent Publication No. 62-35421 describe the regulation of the adhesion, that of the tensile physical properties of the cured substances and the like by the addition of amino group-substituted alkoxysilanes. However, in these aforementioned patents, there is found no specific description on the addition of a silicon compound which has a hetero atom on the carbon atom in the α or β position with respect to the silicon atom, and there are also neither description nor suggestion on the effects of such silicon compounds.